The role of endoscopic ultrasonography in T staging: early gastric cancer and esophageal cancer.

While a number of diagnostic methods have been developed, endoscopic ultrasound (EUS) still takes the most important role in the preoperative evaluation of esophageal cancer. EUS can detect lesions of all esophageal cancer and can accurately perform T staging. In a recent meta-analysis of EUS in esophageal cancer, the sensitivity and specificity of EUS on esophageal cancer were 81.6% and 99.4% in T1, 81.4% and 96.3% in T2, 91.4% and 94.4% in T3, and 92.4% and 97.4% in T4, respectively. The use of EUS can reduce unnecessary surgeries and lead to apply proper treatments to patients. The advance of endoscopic submucosal dissection have necessitated the presurgical detection of early cancer lesions without lymph node metastasis. Understanding the practical meanings of images shown by EUS is important to decide patients for whom endoscopic treatments can be effective. In early gastric cancer, EUS can accurately predict mucosal and SM1 (invasion into the submucosal layer of less than 500 µm from muscularis mucosa) lesions, which are considered as good indications for endoscopic treatments.